Of course it is! But as the others say, try to at least get a sense of the experimental design. But the nitty gritty is a huge part of what research is...troubleshooting, tinkering with the experiment, cloning and re-cloning until you find what you're looking for... No scientist is above what you're doing.
If you're running westerns and they get used in a figure for a paper, it's my opinion that you should have authorship on that paper. But what constitutes authorship varies wildly between labs and between fields. My lab (I am a lab manager) has had numerous undergraduate interns on papers over the years.
It's always worth asking about the PI's policy on authorship--ideally before you start working with the group. And I mean the PI--not the postdoc or grad student. It is a potentially sensitive subject.
Anyway, definitely start asking questions about what you're doing. Is there a weekly group meeting you could start going to? That might help put things in perspective, and be educational, for when you get asked what you did in an interview.